The present invention relates to a magnetic recording and reproducing apparatus such as a videotape recorder utilizing a helical scanning method and a method for checking adjustment statuses of a rotary head thereof.
FIG. 10 to FIG. 12 are provided to illustrate a conventional method for checking adjustment statuses of the rotary heads of a magnetic recording and reproducing apparatus. FIG. 10 is a block diagram showing the configuration of the magnetic recording and reproducing apparatus and an adjustment device connected thereto. FIG. 11 illustrates a method for checking whether a preset value (hereinafter referred to as an X value) of a tracking value, which is a time interval corresponding to a distance X0 between a magnetic tape trace position by a control head and a magnetic tape trace position by the rotary head, is within a predetermined range. FIG. 12 illustrates a method for checking whether the rotary head appropriately traces the recording track on a standard magnetic tape throughout its length (hereinafter referred to as a linearity check).
In a conventional X value check, an operator who adjusts the X value first mounts a standard magnetic tape for checking the X value (a cassette tape, for instance) 71 on the magnetic recording and reproducing apparatus to be checked (video deck to be tested) 50. On the standard magnetic tape 71 for checking the X value, the channel-1 video track 73, which is wider than the rotary head (video head) 12a of the target magnetic recording and reproducing apparatus 50, is recorded, and the channel-2 video track 74 indicated in FIG. 10 is not recorded. The width of the channel-1 video track 73 extends to the right in FIG. 10 and is greater than the width of the rotary head 12a. The operator next brings the magnetic recording and reproducing apparatus 50 into the play mode by using a remote controller 43 or the like, adjusts a manual tracking variable resistor (VR) 61 to decrease a high tracking value to a low value in stages, and manually sets such a tracking value that a video reproduction envelope output S16 obtained by amplifying an output S12 of the rotary head 12a reaches a transition point P1 from a flat portion A1 to an oblique portion A2, as shown in FIG. 11. Then, the operator turns on the X value preset command switch (SW) 62 to return the tracking value to the preset value (which is, the X value), compares a value Vp1 of the video reproduction envelope output corresponding to the tracking value at the point P1 and a value of the video reproduction envelope output corresponding to the X value, and judges, if a difference between the two values is within a predetermined range, that the X value set by the magnetic recording and reproducing apparatus 50 meets the format standard.
Further, a conventional linearity check (which is a compatibility check with respect to the trace status of the rotary heads of the magnetic recording and reproducing apparatus) is made by checking the flatness of the video reproduction envelope output S16 (the amplitude corresponds to a width of an overlapping area of a trace range of the rotary head 12a or 12b and the video track) when the tracking value is varied. The operator who checks the linearity first mounts a standard magnetic tape for the linearity check (a cassette tape, for instance) 72 on the magnetic recording and reproducing apparatus 50 to be checked. On the standard magnetic tape 72 for the linearity check, the channel-1 video track 73 and the channel-2 video track 74, which are narrower than the rotary heads 12a and 12b of the target magnetic recording and reproducing apparatus 50, are recorded. The operator next brings the magnetic recording and reproducing apparatus 50 into the play mode by using the remote controller 43 or the like, and adjusts the manual tracking variable resistor 61 to change the tracking value so that video reproduction envelope output S16 is maximized in both sections in which a drum FF signal S21, which is a control signal to electrically switch the output of the rotary heads 12a and 12b, is high and low (the value is set to five divisions, for instance, as shown in FIG. 12). The operator next changes the tracking value to reduce the maximum value of the video reproduction envelope output S16 (to four divisions, for instance, as shown in FIG. 12). If the minimum value of the video reproduction envelope output S16 in a single cycle of the drum FF signal S21 is greater than or equal to a predetermined value (Z divisions, for instance, as shown in FIG. 12), the flatness of the video reproduction envelope output is judged to meet the requirement and the target magnetic recording and reproducing apparatus 50 is judged to meet the linearity specified on the format.
In the above-mentioned conventional methods for checking adjustment statuses, however, the operator manually adjusts the tracking value, and the operator carries out checks on the X value and linearity of the magnetic recording and reproducing apparatus 50 by measuring a change in the video reproduction envelope output S16, which indicates the relative positional relationship between the rotary head 12a or 12b and the track pattern. Therefore, the operator must have some experience, the time required to make a check depends on the operator, and the check accuracy may also depend on the operator. Since the standard magnetic tapes used for the X value check and linearity check are not the same, the operator gets a heavy workload of changing the tracking value of the different standard tapes separately.
It is an object of the present invention to provide a method for checking adjustment statuses of a magnetic recording and reproducing apparatus which takes some load off the operator and by which differences in experience and capability of operators do not affect the results of the check and the check period, and to provide a magnetic recording and reproducing apparatus which has a structure for executing the method for checking adjustment statuses or for allowing the method for checking adjustment statuses to be executed.
According to one aspect of the present invention, a method for checking adjustment statuses of a magnetic recording and reproducing apparatus is executed after a standard magnetic tape having a reference track recorded using the helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses; and
the method for checking adjustment statuses of the magnetic recording and reproducing apparatus comprises the steps of:
(a) setting a play mode for tracing a track of the standard magnetic tape by the rotary head, according to a command sent from the system control means to the servo means, and then varying the tracking value in stages within a predetermined range;
(b) generating an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values within the predetermined range;
(c) sampling values of the envelope detected output in predetermined positions within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range;
(d) obtaining a tracking value corresponding to a maximum of the values sampled from the envelope detected output; and
(e) outputting a result of a check on whether the preset value is within a predetermined permissible range, according to a difference between the obtained tracking value and the preset value.
Further, values of the envelope detected output are sampled in a plurality of positions within a single tracing in the step (c);and the method for checking adjustment statuses further comprising the step of:
(f) outputting a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the rotary head and a reference track exceeds a permissible value, for each of a plurality of positions within a single tracing, according to whether a range of tracking values corresponding to the sampled values exceeding a predetermined reference value is wider than a predetermined reference width.
Furthermore, the step (b), step (c), step (d), and step (e) may be executed by an external device which exchanges signals with the magnetic recording and reproducing apparatus.
Moreover, the step (b), step (c), step (d), and step (e) may be executed by the system control means.
According to another aspect of the present invention, a method for checking adjustment statuses of a magnetic recording and reproducing apparatus is executed after a standard magnetic tape having a reference track recorded using the helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses; and
the method for checking adjustment statuses comprises the steps of:
(a) setting a play mode for tracing a track of the standard magnetic tape by the rotary head, according to a command sent from the system control means to the servo means, and then varying the tracking value in stages within a predetermined range;
(b) generating an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values with in the predetermined range;
(c) sampling values of the envelope detected output in predetermined positions within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range; and
(f) outputting a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the rotary head and a reference track exceeds a permissible value, for each of a plurality of positions within a single tracing, according to whether a range of tracking values corresponding to the sampled values exceeding a predetermined reference value is wider than a predetermined reference width.
Further, the step (f) may be executed by an external device which exchanges signals with the magnetic recording and reproducing apparatus.
Furthermore, the external device may call a tracking value from a memory means provided in the magnetic recording and reproducing apparatus.
Moreover, the step (f) may be executed by the system control means.
According to still another aspect of the present invention, a magnetic recording and reproducing apparatus comprises: a rotary drum; a rotary head secured on the rotary drum for recording and reproducing information on a magnetic tape using a helical scanning method; a control head for recording and reproducing a control signal on the magnetic tape; a servo means for controlling a tracking value corresponding to a distance from a magnetic tape trace position by the control head to a magnetic tape trace position by the rotary head; and a system control means for controlling operation of the whole apparatus;
the magnetic recording and reproducing apparatus further comprises: a first terminal for outputting an envelope output from the rotary head for each of a plurality of tracking values within the predetermined range; a second terminal for outputting a tracking value set by the servo means; and a third terminal for inputting a command to the system control means;
wherein, after a standard magnetic tape having a reference track recorded using the helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses, the system control means sends a command to the servo means so that a play mode for tracing a track of the standard magnetic tape by the rotary heads is set, and then varies the tracking value in stages within a predetermined range; and the first, second, and third terminals are connected to an external device, which generates an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values within the predetermined range, samples values of the envelope detected output in predetermined positions within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range, obtains a tracking value corresponding to a maximum of the values sampled from the envelope detected output, and outputs a result of a check on whether a preset value is within a predetermined permissible range, according to a difference between the obtained tracking value and the preset value.
Further, the external device connected to the first, second, and third terminals samples values of the envelope detected output in a plurality of positions within a single tracing and outputs a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the rotary head and a reference track exceeds a permissible value, for each of a plurality of positions within a single tracing, according to whether a range of tracking values corresponding to the sampled values exceeding a predetermined reference value is wider than a predetermined reference width.
According to a further aspect of the present invention, a magnetic recording and reproducing apparatus comprises: a rotary drum; a rotary head secured on the rotary drum for recording and reproducing information on a magnetic tape using a helical scanning method; a control head for recording and reproducing a control signal on the magnetic tape; a servo means for controlling a tracking value corresponding to a distance from a magnetic tape trace position by the control head to a magnetic tape trace position by the rotary heads; and a system control means for controlling operation of the whole apparatus;
the magnetic recording and reproducing apparatus further comprising: a first terminal for outputting an envelope output from the rotary head for each of a plurality of tracking values within the predetermined range; a second terminal for outputting a tracking value set by the servo means; and a third terminal for inputting a command to the system control means;
wherein, after a standard magnetic tape having a reference track recorded using the helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses, the system control means sends a command to the servo means so that a play mode for tracing a track of the standard magnetic tape by the rotary heads is set, and then varies the tracking value in stages within a predetermined range; and the first, second, and third terminals are connected to an external device, which generates an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values within the predetermined range, samples values of the envelope detected output in predetermined positions within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range, and outputs a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the rotary head and a reference track exceeds a permissible value, for each of a plurality of positions within a single tracing, according to whether a range of tracking values corresponding to the sampled values exceeding a predetermined reference value is wider than a predetermined reference width.
Further, the apparatus may comprise a memory means for storing a tracking value varied within a predetermined range, wherein the external device calls the tracking value from the memory means.
According to a still further aspect of the present invention, a magnetic recording and reproducing apparatus comprises: a rotary drum; a rotary head secured on the rotary drum for recording and reproducing information on a magnetic tape using a helical scanning method; a control head for recording and reproducing a control signal on the magnetic tape; a servo means for controlling a tracking value corresponding to a distance from a magnetic tape trace position by the control head to a magnetic tape trace position by the rotary heads; and a system control means for controlling operation of the whole apparatus;
wherein, after a standard magnetic tape having a reference track recorded using a helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses, the system control means sends a command to the servo means so that a play mode for tracing a track of the standard magnetic tape by the rotary heads is set, and then varies the tracking value in stages within a predetermined range, generates an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values within the predetermined range, samples values of the envelope detected output in a predetermined position within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range, obtains a tracking value corresponding to a maximum of the values sampled from the envelope detected output, and outputs a result of a check on whether a preset value is within a predetermined permissible range, according to a difference between the obtained tracking value and the preset value.
Further, when the system control means samples values of the envelope detected output, the values of the envelope detected output are sampled in a plurality of positions within a single tracing by the rotary head; and the system control means outputs a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the rotary head and a reference track exceeds a permissible value, for each of a plurality of positions within a single tracing, according to whether a range of tracking values corresponding to the sampled values exceeding a predetermined reference value is wider than a predetermined reference width.
According to a still further aspect of the present invention, a magnetic recording and reproducing apparatus comprises: a rotary drum; a rotary head secured on the rotary drum for recording and reproducing information on a magnetic tape using a helical scanning method; a control head for recording and reproducing a control signal on the magnetic tape; a servo means for controlling a tracking value corresponding to a distance from a magnetic tape trace position by the control head to a magnetic tape trace position by the rotary heads; and a system control means for controlling operation of the whole apparatus;
wherein, after a standard magnetic tape having a reference track recorded using a helical scanning method is loaded into the magnetic recording and reproducing apparatus and the system control means receives a command to start a play mode for checking adjustment statuses, the system control means sends a command to the servo means so that a play mode for tracing a track of the standard magnetic tape by the rotary heads is set, then varies the tracking value in stages within a predetermined range, generates an envelope detected output having a magnitude corresponding to an output from the rotary head for each of a plurality of tracking values within the predetermined range, samples values of the envelope detected output in a plurality of predetermined positions within a single tracing by the rotary head, for each of the plurality of tracking values within the predetermined range, and outputs a result of a check on whether adjustment has been made so that a width of an overlapping area of a trace range by the rotary head and a reference track exceeds a permissible value, for each of a plurality of positions within a single tracing, according to whether a range of tracking values corresponding to the sampled values exceeding a predetermined reference value is wider than a predetermined reference width.